Use long running session in builder

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

Add incremental context send support

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

cli/command/system/df.go

@@ -57,11 +57,12 @@ func runDiskUsage(dockerCli *command.DockerCli, opts diskUsageOptions) error {
 			Output: dockerCli.Out(),
 			Format: formatter.NewDiskUsageFormat(format),
 		},
-		LayersSize: du.LayersSize,
-		Images:     du.Images,
-		Containers: du.Containers,
-		Volumes:    du.Volumes,
-		Verbose:    opts.verbose,
+		LayersSize:  du.LayersSize,
+		BuilderSize: du.BuilderSize,
+		Images:      du.Images,
+		Containers:  du.Containers,
+		Volumes:     du.Volumes,
+		Verbose:     opts.verbose,
 	}
 
 	return duCtx.Write()

cli/command/system/prune.go

@@ -9,6 +9,7 @@ import (
 	"github.com/docker/cli/opts"
 	units "github.com/docker/go-units"
 	"github.com/spf13/cobra"
+	"golang.org/x/net/context"
 )
 
 type pruneOptions struct {
@@ -49,6 +50,7 @@ const (
 	- all volumes not used by at least one container
 	- all networks not used by at least one container
 	%s
+	- all build cache
 Are you sure you want to continue?`
 
 	danglingImageDesc = "- all dangling images"
@@ -97,6 +99,12 @@ func runPrune(dockerCli command.Cli, options pruneOptions) error {
 		fmt.Fprintln(dockerCli.Out(), output)
 	}
 
+	report, err := dockerCli.Client().BuildCachePrune(context.Background())
+	if err != nil {
+		return err
+	}
+	spaceReclaimed += report.SpaceReclaimed
+
 	fmt.Fprintln(dockerCli.Out(), "Total reclaimed space:", units.HumanSize(float64(spaceReclaimed)))
 
 	return nil